Biomechanics of Hip Joint PDF

section.1 Biomechanics of hip joint preencoded.png Muscles of the Hip Joint It is important to remember when studying the muscular function of the pelvic and hip region, that these muscles work to either move the pelvis on the femur or move the femur on the pelvis. For exampl...

section.1 Biomechanics of hip joint preencoded.png Muscles of the Hip Joint It is important to remember when studying the muscular function of the pelvic and hip region, that these muscles work to either move the pelvis on the femur or move the femur on the pelvis. For example, the hip flexors will either flex the hip on the stable pelvis or tilt the pelvis anteriorly on the stable femur. These functions of the muscles at the pelvis and hip are determined by whether the limb is moving in weight-bearing or non-weight bearing. preencoded.png In weight-bearing, the femur is stationary, and movement occurs as the pelvis moves on the femur. On the other hand, in the open chain or non-weight bearing position, the femur moves on the stable pelvis. The pelvic and hip muscles are adaptable and utilize their structural features, such as their size, length, or line of pull, to meet the joint’s functional task demands. preencoded.png preencoded.png Flexors IRS PT The hip flexors act primarily as a mover of the limb in the open kinematic chain by advancing the lower extremity during the swing phase in gait, lifting the limb up steps, and propelling objects in various activities such as in kicking. There are actually nine muscles that cross the anterior hip joint. Of those nine, five muscles are primary hip flexors. Listed in order of their significant contribution 1 Iliopsoas 2 Rectus Femoris strongest and most consistent hip flexor It crosses over the Crosses both the hip and knee joints. anterior middle aspect of the joint, so its line of pull is always well aligned to act as a hip flexor 3 Sartorius 4 Pectineus Longest muscle in the body, contributes to flexion, Located on the medial side of the hip, contributes to flexion abduction, and external rotation. and adduction. TWO JOINT MUCLE Sartorius ,Rectus,TFL 5 Tensor fascia lata TFL flexes and medially rotates the hip, because its position makes it is a very strong abductor, preencoded.png preencoded.png Extensors The primary hip extensor muscles are located in the posterior hip and thigh and include the gluteus maximus, biceps femoris, semitendinosus, semimembranosus, and posterior portion of the adductor magnus. Gluteus Maximus Hamstring Muscles Adductor Magnus The largest and most powerful Biceps femoris, semitendinosus, The largest adductor muscle, hip extensor. and semimembranosus, its posterior fibers contribute contribute to both hip to hip extension. extension and knee flexion. preencoded.png Abductors The hip abductors are responsible for moving the thigh away from the midline of the body. They are essential for maintaining balance during walking and running. The primary hip abductors include the gluteus medius, gluteus minimus, and tensor fascia latae. GT Muscle Action Gluteus Medius Abduction, medial rotation Gluteus Minimus Abduction, medial rotation Tensor Fascia Latae Abduction, flexion, medial rotation preencoded.png Adductors The hip adductors are responsible for moving the thigh towards the midline of the body. They are essential for activities like walking, running, and kicking. The primary hip adductors include the pectineus, adductor brevis, adductor longus, adductor magnus, and gracilis. Pectineus Adductor Brevis GAP Adductor Longus Adductor Magnus The largest adductor muscle, contributes to adduction, extension, and medial rotation. Gracilis preencoded.png Lateral Rotators The six small lateral rotators of the hip are located in the posterior gluteal region and are covered by the gluteus maximus, they are obturator internus and externus, the gemellus superior and inferior, quadratus femoris and piriformis muscles. This can be assisted by the posterior fibers of the gluteus medius and minimus and the superior fibers of the gluteus maximus. satic nerve preencoded.png Medial Rotators There are no specific muscles whose line of pull provides pure hip medial rotation in the transverse plane; rather, medial rotation is performed by several muscles that also provide other primary motions. These multipurpose muscles include the anterior gluteus medius, gluteus minimus, pectineus, TFL, and adductors. In addition, the medial hamstring muscles can also contribute to medial rotation Gluteus Medius & Minimus go a head pass test Contribute to medial rotation, especially when the hip is flexed. Pectineus & TFL Contribute to medial rotation, but their primary actions are flexion and adduction. Adductors Contribute to medial rotation, but their primary action is adduction. Medial Hamstrings Contribute to medial rotation, but their primary action is extension. preencoded.png Factors Affecting the Roles of the Muscles of the Pelvis and Hi — A muscle’s role is determined by several factors, including the: number of joints it crosses position of the other joints which the muscle crosses size and cross section of the muscle, including fiber type/arrangement leverage, determined by length and distance of attachment and line of pull from joint axis type of muscle contraction—eccentric, concentric, or isometric segment’s position relative to gravity movement task requirement load being moved or stabilized; and speed of motion. preencoded.png Factors Affecting the Roles of the Muscles of the Pelvis and Hi — In addition to these factors, the pelvis and hip provide an important functional contrast in the lower extremity between the weight-bearing and non-weight bearing demands and how those demands are met. When analyzing the functional contributions of various muscles of the pelvis and hip, it is important to consider all of the factors listed above with a special emphasis on three important kinesiological concepts: the line of pull and leverage affecting the muscle’s action one-joint versus two-joint muscles whether the motion is an open kinematic chain or a closed kinematic chain activity preencoded.png preencoded.png preencoded.png preencoded.png preencoded.png Weakness of Psoas Major Weakness of the psoas major. Such weakness could produce difficulties in tasks. Although active hip flexion is an important element of normal locomotion. 1 Decreased Hip Flexion Strength Difficulty with activities like lifting the leg and climbing stairs. 2 Minimal Impact on Gait Slight-to-moderate weakness may not significantly affect normal walking. 3 Potential for Compensation Other muscles may compensate for the weakness, minimizing functional limitations. preencoded.png Tightness of Psoas Major Tightness of the psoas major restricts hip extension range of motion (ROM). It may also limit trunk side-bending flexibility. In the upright posture, tightness of the psoas major is often manifested by increased lumbar extension, that is, by an excessive lumbar lordosis. This posture results from the pull on the lumbar vertebrae toward the femur and simultaneous compensation of backward-bending elsewhere in the spine for the individual to keep the eyes on the horizon. Lumbar Lordosis An excessive inward curve of the lower back, often associated with psoas major tightness. preencoded.png Weakness of Iliacus Weakness of the iliacus, another primary hip flexor, decreases hip flexion strength. The functional effects are similar to those with weakness of the psoas major. While these muscles are often weak together, in some cases, such as in a spinal cord lesion, the psoas major may be spared while the iliacus is affected. 1 Decreased Hip 2 Potential for 3 Passive Support Flexion Strength Compensation The anterior capsule and Similar functional limitations Other muscles may compensate ligaments can provide passive as with psoas major weakness. for the weakness, minimizing support to prevent hip functional limitations. hyperextension in quiet standing. preencoded.png Tightness of iliacus Tightness of the iliacus reduces hip extension ROM. In the standing position, tightness of the iliacus results in an anterior pelvic tilt that is accompanied by hyperextension of the lumbar spine, if available, for the individual to maintain vision of the horizon. Therefore, as seen with tight psoas major, tight iliacus frequently leads to an increased lumbar lordosis. If, however, the subject lacks hyperextension flexibility in the spine, tightness of the iliacus or psoas major can produce a forward lean and a flattened lumbar spine in upright posture. preencoded.png weakness of gluteus maximus Weakness of the gluteus maximus results in decreased strength of hip extension and lateral rotation. A classic gait pattern resulting from gluteus maximus weakness, knownas the gluteus maximus lurch. The lurch is a rapid hyperextension of the trunk prior to, and continuing through, heel contact on the side of the gluteus maximus weakness. It has been suggested that the backward “lurch” moves the center of mass of the HAT weight to a position posterior to the hip joint, thus eliminating the need for the gluteus maximus to extend the hip. However, it is also important to recognize that such a significant gait deviation is more likely a result of weakness of other hip extensors in addition to the gluteus maximus preencoded.png tightness of gluteus maximus Tightness of the gluteus maximus limits hip ROM in flexion and medial rotation and, perhaps, adduction, although its effects in the frontal plane are more difficult to ascertain since it appears to be both an abductor and adductor. Athletes such as runners who have strongly developed gluteus maximus muscles can exhibit such tightness. Because hip movement is intimately related to low back movement, tightness of the gluteus maximus may produce excessive movement in the lumbar spine. preencoded.png THANK YOU preencoded.png